What is square foot?
A square foot is a unit of area in imperial and US customary systems equal to 144 square inches. It is commonly used in the United States for real estate listings, floor plans, and building layouts.
Real-world uses
Square feet are the primary unit for real estate in the United States, Canada, and parts of South Asia. Office space, apartment listings, and retail floor plans are quoted in sq ft. Flooring, tiles, and paint coverage are sold per square foot in these markets.
History
The square foot derives directly from the foot, which has been used since ancient times. It became the de facto real estate standard in the United States and remains deeply entrenched in American property markets despite the global shift toward metric units.
Common mistakes
Forgetting that square footage is an area measure, not a length. A 1,000 sq ft apartment is not 1,000 feet long. Also, nominal tile sizes often include grout spacing, so actual coverage per tile is slightly less than the stated size.
What is acre?
An acre is a unit of area in imperial and US customary systems equal to 43,560 square feet. It is the standard unit for measuring agricultural land, property lots, and parks in the United States and United Kingdom.
Real-world uses
Acres are used for land parcels, farm sizes, and real estate in the US, UK, and some Commonwealth countries. Zoning laws often specify minimum lot sizes in acres. An American football field (including end zones) is about 1.32 acres.
History
The acre originated in medieval England as the amount of land a yoke of oxen could plough in one day. The word comes from Old English "æcer." It was standardized as a strip 1 furlong (660 ft) by 1 chain (66 ft), yielding 43,560 square feet.
Common mistakes
Assuming an acre is a square measure with specific dimensions—it is 43,560 sq ft but can be any shape. Also, confusing acres with hectares: 1 acre ≈ 0.405 hectares, so roughly 2.5 acres make one hectare.
When is this conversion used?
Converting square foot to acre is useful in the area domain when comparing values across different measurement standards or applying formulas that require a specific unit.
Worked examples
1 square foot = 0.00002296 acre
1 acre = 4,046.8564224 square metre
How to convert square foot to acre
To convert square foot to acre, multiply the value by 0.00002296.
To convert acre back to square foot, multiply by 43,560.
Measurement standards
The square metre is the SI derived unit of area. The hectare (10,000 m²) is accepted for use with the SI by the BIPM, particularly for land measurement, though it is not an SI unit itself.
Did you know?
Vatican City, the world's smallest independent state, covers just 0.44 km² (about 109 acres) — smaller than many golf courses. By contrast, Russia spans over 17.1 million km², nearly 39 million times larger.
Quick reference: square foot to acre
| square foot | acre |
|---|---|
| 0.1 | 0.0000023 |
| 0.5 | 0.00001148 |
| 1 | 0.00002296 |
| 2 | 0.00004591 |
| 5 | 0.00011478 |
| 10 | 0.00022957 |
| 25 | 0.00057392 |
| 50 | 0.00114784 |
| 100 | 0.00229568 |
| 250 | 0.00573921 |
| 500 | 0.01147842 |
| 1,000 | 0.02295684 |
Common values
| square foot | acre | |
|---|---|---|
| A4 paper | 0.66736245 square foot | 0.00001532 acre |
| Parking space | 134.54888021 square foot | 0.00308882 acre |
| Tennis court | 2,807.98131041 square foot | 0.06446238 acre |
| Football field (soccer) | 76,854.32037531 square foot | 1.76433242 acre |
| Central Park, NYC | 36,704,934.52098015 square foot | 842.6293508 acre |